My bet as well, Quite normal for people to not re-build heads during an engineoverhaul, and often old valve guide seals leak, and when they do, it's blue smoke at start up, that goes away in a couple of minutes, but results in little to no oilconsumption.

Gee, I hate to jump in on this but I have a Perkins 4-108 that deposits a lot of black soot on the transom after motoring awhile. The smoke is not blue, but black. It starts and runs fine but will not come up to full rated revs.

I have been told that blue smoke means oil is in the exhaust and black means that unburnt diesel is in the exhaust. This seems right to me. I'm surprised more mechanic "sperts" haven't spoken up on this.

In my case, I think my prop is over-pitched. I was told to check the timing mark on my fuel injector system and that seems OK. The injectors are OK. The air intake is clean. From what I understand, if the timing is good and you get enough air for the proper amount of fuel then you should be good at the rated max RPM.

I am not sure if blue smoke would soot up your transom the same as black smoke but the causes and repairs are very different for each so it is important to sort that out.

I'm going to start a separate thread about the effect of motoring at different RPMs on smoke.

I have had a few of these engines I bet one of two things have happened , 1/wrong type of cylinder head casket there are two types for these engines one where you do just one torque setting the other where you torque on rebuild then re set at 50 hrs , and the casket usually blows between No 1 & 2 cylinder if you have the LD series then it's a one torque casket required

I have had a few of these engines I bet one of two things have happened , 1/wrong type of cylinder head casket there are two types for these engines one where you do just one torque setting the other where you torque on rebuild then re set at 50 hrs , and the casket usually blows between No 1 & 2 cylinder if you have the LD series then it's a one torque casket required

Your service manual or memory, differs from my manual which says "re-torque after the engine has warmed up". A re-torque after 15-30 hours is required on 4-108 engines only. There is an oil passage to the rocker arms between cylinders 2 and 3..

Thanks to everyone who has posted replies and suggestions re , blue smoke and sooty exhaust. The most puzzling thing is that smoke only became apparent after re launching after a 6 month lay up. I re torqued the head at sea after 40 hours and changed the oil on lay up at 47 hours. One Caribbeanmechanic suggested introducing 2 tablespoons of Vim scouring powder to the air intake with the engine running . Any comments?
At this time I have no access to any trustworthy trained diesel mechanic but have resolved to change to mono grade oil and and to try an injector cleaner/ conditioner . The injector pump probably requires fine adjustment but as far as I know incomplete combustion results in black smoke whereas the issue here is blue smoke . Engine hours currently 83 and if there is any oil usage it is negligible as I can't detect a drop on the dipstick .

Your service manual or memory, differs from my manual which says "re-torque after the engine has warmed up". A re-torque after 15-30 hours is required on 4-108 engines only. There is an oil passage to the rocker arms between cylinders 2 and 3..

I would think if it where a gasket problem from an oil passage, it wouldn't stop smoking and would show a decrease on the dip stick?

Vim powder? Never heard of it but have heard of Bon Ami for that use. I would only use that trick on an old engine. The more accecpted (?) way of using Bon Ami is when the engine is apart and you don't have any new rings. You make up a paste of Bon Ami and smear it on the cylinder walls. Put the piston and rings back in there and work it back and forth till you think you have done something, then wash it out. Is is a mineral you know, Limestone or something. I would not want that residue inside my engine.
Just run the dog **** out it for a while with straight mineral oil and see what happens. And check your oil filter for metal.

I would think if it where a gasket problem from an oil passage, it wouldn't stop smoking and would show a decrease on the dip stick?

Hard to tell how much it would use but I think you are right about it the smoking part. I doubt it's a head gasket problem. They usually blow things out, not suck them in. This thing has like a 22:1 compression ratio, way more than oil pressure.

Thanks to everyone who has posted replies and suggestions re , blue smoke and sooty exhaust. The most puzzling thing is that smoke only became apparent after re launching after a 6 month lay up. I re torqued the head at sea after 40 hours and changed the oil on lay up at 47 hours. One Caribbean mechanic suggested introducing 2 tablespoons of Vim scouring powder to the air intake with the engine running . Any comments?
At this time I have no access to any trustworthy trained diesel mechanic but have resolved to change to mono grade oil and and to try an injector cleaner/ conditioner . The injector pump probably requires fine adjustment but as far as I know incomplete combustion results in black smoke whereas the issue here is blue smoke . Engine hours currently 83 and if there is any oil usage it is negligible as I can't detect a drop on the dipstick .

So, i guess you got new pistons, rings, sleeves gaskets etc... then maybe the blue smoke is just a set of rings dont fit properly , maybe they need some time to adjust and thats all, or maybe a valve seal , but again if the blue smoke is just at startup and later is gone is quite normal in those old perkins, are you sure the valve head is in the rebuild list?? i mean easy to see, disconect the air filter housing and with your finger try to found black soot deposits or kind of oil gummy black stuff inside of the air intake in the head, in a genuine rebuild the head come sparking clean,,, in the 4236 only 3 places for the oil to found a way in the combustión chamber, 1 Rings, 2 valves seals 3 by the air intake filter housing... If is only at startup i suspect a valve seal , when you stop your engine the oil can rest in the seal droping a small amount inside and when the engine is fired again som blue smoke is normal, if the smoke is present when the engine is hot and after few minutes i suspect pistons rings...

If you feel better i can say i own a 4236 for quite some years , 4400 hours in the meter, wáter temp 80 all the time , between 40 and 60 psi oil presure, start really well even in cold days, idle at 800 like a champ, and i have some black soot deposits in the exhaust and even some small traces of blue smoke at startup, after few minutes the exhaust is clear,,, a good mechanic some time tell me, those engines outlast you and the boat, if wáter temp and oil presure Readings are ok, and no oil burning between oil changes just dont worry, they are not yanmars or hig rev engines, they smoke, they are noisy, and sometime they are leaky, but they are tough engines and probably one of the best perkins around ... a workhorse!!!

All this talk of a Perkins lasting forever is not my experience. Ours had only 4,500hrs and it needs a ovhl. The head is junk and needs everything. Valves, seats, guides, re- surface. The Block needs liners, pistons, rings, bearings and who knows what else. I never ran it out of oil or nothing. The over temp alarm has gone off numerous times because of stupid cooling system problems but that is kind of normal right?

So, i guess you got new pistons, rings, sleeves gaskets etc... then maybe the blue smoke is just a set of rings dont fit properly , maybe they need some time to adjust and thats all, or maybe a valve seal , but again if the blue smoke is just at startup and later is gone is quite normal in those old perkins, are you sure the valve head is in the rebuild list?? i mean easy to see, disconect the air filter housing and with your finger try to found black soot deposits or kind of oil gummy black stuff inside of the air intake in the head, in a genuine rebuild the head come sparking clean,,, in the 4236 only 3 places for the oil to found a way in the combustión chamber, 1 Rings, 2 valves seals 3 by the air intake filter housing... If is only at startup i suspect a valve seal , when you stop your engine the oil can rest in the seal droping a small amount inside and when the engine is fired again som blue smoke is normal, if the smoke is present when the engine is hot and after few minutes i suspect pistons rings...

If you feel better i can say i own a 4236 for quite some years , 4400 hours in the meter, wáter temp 80 all the time , between 40 and 60 psi oil presure, start really well even in cold days, idle at 800 like a champ, and i have some black soot deposits in the exhaust and even some small traces of blue smoke at startup, after few minutes the exhaust is clear,,, a good mechanic some time tell me, those engines outlast you and the boat, if wáter temp and oil presure Readings are ok, and no oil burning between oil changes just dont worry, they are not yanmars or hig rev engines, they smoke, they are noisy, and sometime they are leaky, but they are tough engines and probably one of the best perkins around ... a workhorse!!!

You expressed my valve guide theory better than me. Also if it's not burning oil and runs well don't worry about it. Have a brush to clean around the exhaust one in awhile. I know nothing about the vim, whatever that is. Don't think feeding a powder into an engine with 47 hrs. on it is a great idea.

My Perkins 4236 was completely rebuilt in South Africa last year . After 47 hours I changed the oil and laid up the boat on the hard in Trinidad. There was no smoke and the exhaust was clean at this time. Launched in March this year And motored for about 4 hours on passage to Grenada . I was horrified to find the hull around the exhaust covered in black soot. The motor has now done approximately 80 hours since the rebuild and on startup is producing lots of blue smoke . This appears to diminish to nothing when the motor reaches normal running temperature. I have not detected any drop in the oil level on the dipstick. A local mechanic diagnosed a worn injector pump so I ordered a rebuilt pump from the USA but that does not appear to have made any difference to the smoking.
The next mechanic I consulted said the cylinders are glazed and the motor needs new piston rings. I find this hard to believe as the motor has run only a few hours without a load. Please, can anyone help?

You may be worrying about nothing. Give it some time. My 4-108 always show a bit of oil smoke for the first minute or so. Not an oil user though Started with 350 hours on it.

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